1. Field of the Invention
The present invention generally relates to packaging of integrated circuit devices, and is particularly related to a thin film capacitor formed on a silicon/silicon oxide substrate interposer, which is connected to a ceramic substrate and to a method of making the same.
2. Description of the Related Art
As integrated circuit (IC) chips have increased in complexity and decreased in size, the formation of interconnections between IC chips has also greatly increased in complexity. Many devices, such as computers, use a number of separate IC chips. For example, a computer may include one or more central processing units, an arithmetic processor, various controller and memory chips, input/output interface chips, etc. Conventionally, each IC chip is mounted individually in a separate package that is connected to a printed circuit board, for example, a computer “motherboard,” which provides power and signal interconnections to the mounted IC chips. However, when a device requires a large number of IC chips, individually packaging and mounting each IC chip greatly increases the printed circuit board area required to interconnect all the IC chips. Additionally, as device speed has increased, it has become more important to minimize the path lengths between IC chips, themselves, and the other electronic components connected to the IC chips.
To decrease printed circuit board space, distance between IC chips and the complexity of interconnections, many devices now use multichip modules (MCMs) that incorporate a number of IC chips into one package. Using one package reduces the distance between IC chips, thus, permitting greater device speeds. The multichip modules usually provide power and signal interconnections to the individual IC chips from an underlying ceramic substrate.
Multichip modules may be two-dimensional, that is, all the IC chips of a package are mounted on a planar substrate, or three-dimensional, where IC chips are mounted above or below a ceramic substrate, another IC chip, or an interposer. An interposer is a structure on which various electronic components and interconnections are formed and is usually located between an IC chip and a ceramic substrate, another interposer, or a printed circuit board.
As the switching speed of devices increases, it is important to provide a decoupling capacitance in close proximity to the IC chips of the multichip module. Conventionally, a discrete capacitor has been mounted on a surface of a ceramic substrate or a decoupling capacitance has been incorporated into the ceramic substrate. The former approach uses valuable real estate on the surface of the ceramic substrate and does not place the discrete capacitor in close proximity to the IC chip, while the latter approach increases the complexity of the ceramic substrate and thus, decreases yields.